Hi @kevin,
From the Southern of Sweden - via Telia's NB-IOT Network - I get this:
>>> send_at_cmd_pretty('AT+SQNHPLMN?')
+SQNHPLMN: "23820","23820","23820"
OK
>>>
and for you who would like to look it up: http://www.numberportabilitylookup.com/networks?s=